An embodiment relates generally to detection of a wet road surface.
Precipitation on a driving surface causes several different issues for a vehicle. For example, water or snow on a road reduces the coefficient of friction between the tires of the vehicle and the surface of the road resulting in vehicle stability issues. Detection of water or snow on a road of travel is typically determined by a host vehicle sensing for precipitation on the road utilizing some sensing operation which occurs when the precipitation is already impacting the vehicle operation such as detecting wheel slip. As a result, the vehicle must monitor its own operating conditions (e.g., wheel slip) against dry pavement operating conditions for determining whether precipitation is present. As a result, such systems may wait for such a condition to occur or may introduce excitations to the vehicle for determining whether the condition is present (e.g., generating sudden acceleration to the driven wheels for invoking wheel slip if the precipitation is present).
In some applications where captured sensor data are used, e.g. images, the scale of the image analyzed may hinder the detection results. That is, conditions of a road surface may change as a vehicle travels along a road. For example, for a snow covered road, due to wind and other elements, the vehicle road may have patches of a snow covered surface and a dry covered surface. As a result, depending on the scale and when the image is captured, the respective road surface detection technique may actually not detect the snow covered surface.